This invention relates to a concrete finishing tool which allows a user to adjust the angle of a float as it is being pulled towards or pushed away from the user.
In providing a smooth finish to large slabs of concrete, a tool called a float is used to induce the fine particles of sand and concrete to come to the surface of the slab for subsequent finish troweling. Since the concrete is still unset, it is undesirable to walk over its surface, because this will disturb the natural settling and separation of the particles. It is desired that the fine particles come to the surface and that the larger particles distribute themselves through the lower regions of the concrete. This segregation of particles is facilitated by the use of the float which the user drags back and forth over the surface of the slab.
Long handles are used so that a large surface area may be reached from a single point. Employing long handles presents a problem in using the float. If the edge of the float is slanted downward in the direction of motion, the float will cut into the concrete rather than smoothing its surface. Since the float is drawn towards the user and then pushed away, it is necessary to change the angle of incidence by either lowering the long handle when pushing the float or raising it when pulling the float. This works adequately when the length of the handle is, for example, less than about 12 feet. If, for example, a very long handle 20 feet in length is used, the height required to lift the one end of the handle to prevent gouging the concrete surface will, in many instances, be out of reach of the user or in the range where he can no longer exert sufficient force to pull the float. Similarly, when pushing the float away, to correct the tilt edge of the float, the handle may have to be lower than the surface of the concrete being prepared.
The invention relates to an improved concrete float adjusting de vice which provides a reliable and easy way to change the tilting angle of incidence of the float by the user""s simple rotation of the handle at some remote distance from the float. The tilt control mechanism is characterized by a dual spirally slotted shaft which, because of a surrounding, scaled protective sleeve, can be kept free of concrete and abrasive materials which damage bearing surfaces during use and greatly reduce the life of the mechanism. The use of the protective sleeve around the shaft further cuts down on the cleanup time required and improves overall efficiency at the finishing worksite.
The concrete float adjusting device includes a base having a pail of spaced apart, upstanding portions and a planar support plate which is attached to a concrete float. An elongated rotatable shaft has a reduced diameter or narrow front end portion surrounded by support bearings, a handle-receiving rear end portion, and an intermediate portion formed with a pair of spiral slots. A pivot bearing has a lower end pivotally coupled to the base, and an upper end encircling the reduced diameter, bearing supported front end portion of the shaft such that the shaft is rotatably received in the upper end of the pivot bearing. A protective sleeve surrounds the intermediate portion of the shaft for slidable movement thereon and protectively covers the spiral slots to prevent accumulation of material therein. The protective sleeve is provided with a pair of circular seals at opposite ends thereof which are engageable with the shaft. A follower sleeve extends completely around the intermediate portion of the shaft and the protective sleeve. The follower sleeve is integrally coupled to the protective sleeve such that the follower sleeve and the protective sleeve are slideable as a unit along the intermediate portion of the shaft. A pair of upper pivot shafts having outer ends is located on opposite sides of the follower sleeve. The upper pivot shafts project through the follower sleeve and the protective sleeve and have inner ends engaged in the spiral slots. A pair of lower pivot shafts has outer ends located on opposite sides of the upstanding portions of the base, and inner ends projecting into upstanding portions of the base. A pair of shiftable link arms is provided, each having an upper end pivotally connected to one of the upper pivot shafts and a lower end pivotally connected to one of the lower pivot shafts. Rotation of the shaft, such as by a handle connected thereto, causes the follower sleeve and protective sleeve to move linearly along the shaft as the inner ends of the upper pivot shafts follow a path of the spiral slots. This motion results in transmitting movement of the follower sleeve and protective sleeve via the shifting of the link arms to the base which is pivotally coupled to the pivot bearing so as to change the angular relationship between the float and the shaft.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.
The drawings illustrate the best mode presently contemplated of carrying out the invention.
In the drawings:
FIG. 1 is a side elevational view, in partial cross section, of the concrete float adjusting device of the present invention with the base support plate and float tilted a maximum distance in one direction;
FIG. 2 is a view similar to FIG. 1 with the base support plate and float tilted a maximum distance in the opposite direction of FIG. 1;
FIG. 3 is a partial cross sectional view of the concrete float adjusting device;
FIGS. 4A-4C are respective plan, end and side elevational views of the base;
FIG. 5 is a side elevational view of the shaft;
FIGS. 6A and 6B are respective side elevational and end views oaf the pivot bearing;
FIGS. 7A and 7B are respective end and cross sectional views of the protective sleeve;
FIGS. 8A and 8B are respective side elevational and front views of the follower sleeve; and
FIG. 9 is an elevational view of one of the link arms.